its early on with this project, I was going to wait until its completed, but not sure when that will be, so Ill give you a sneak peak. I've been using a sound system in one of my model planes, and over time have become friendly with the guy who makes them, helping him with various things. I got thinking about the 4 foot fireboat I have, and how cool it would be to have a sound unit. So, to cut a long story short, I knew he had a plane sound with twin Merlin's for a bomber, and I use a merlin for my P51 Mustang model. After a serious amount of pestering, I got him to modify one of the 5 stock sounds on his Boat sound unit, using the twin Merlin sound from the planes. It took some work, getting rid of the propeller sound on the start up and shut down sequence. I ran it for the first time last night, but forgot to take spare batteries, and a small screwdriver to adjust the settings, so couldnt change the settings, in particular, the volume was set way too loud, losing some of the clarity of sound.

This is pretty close to the real engines, which where v8 meteor, this sound is an actual recording of the v12 Merlin, its doubled up, and staggered, so you can hear the two engines running. It has start up and shut down sequence, it isn't clever enough to read reverse unfortunately.

Its a speakerless system, using transducers instead of speakers, which are much louder, smaller and lighter. They rely on vibrations, they are epoxied to the hull, and the whole boat becomes the speaker! Its the first time I've done this, and its pretty new on the market for boats, planes have been going for a few years. I've realised that whilst I put them above the waterline, I didn't account for the roll of the hull, when one (there is one on either side) goes below the waterline it muffles the vibrations, and causes a funny sort of gurgling noise, ah well, like I say, its early days! Still a bit of tweaking to do, but you get the idea.Stock sounds are Turbo cat diesel, Johnson outboard, evenrude outboard, mercule v8, steam. They also have aux sounds, such as ships bell, steam whistle, horn, seagulls etc. I think on my system the Johnson is dropped in lieu of the twin merlin sound.

Hi Doug,they are from mrrcsound, available on the website, they are called tt25 transducers.

Having played with these at length with model planes, I now know the hull thickness isn't enough. The thicker the material, the deeper the sound, but you lose volume. Unfortunately once epoxied on, they don't come off, until the epoxy goes brittle, which does happen as the vibrations cause this. If I try to pull them off now, they will break. I have too much volume, and not enough depth. With a plane, due to distance away from operator, you need the volume, with the boat, they don't go anywhere near as far away from the operator, so I messed up here😭 Ill turn it down a lot, see how that works out

Hi pm, many thanks 👍 Didn't find them on the MBW ? so I searched, and found this via a review which said 'good but expensive - try these'!https://www.parts-express.com/dayton-audio-daex25vt-4-vented...Same thing - half the price!? 😉The other MrRC bits look interesting as well; sound package chips etc, ta for the tip. Cheers Doug 😎

Hmmm! Dayton prices are good for US users, but not for us 🤔 Shipping, tax and duty more than doubles the price 😡 Hey ho! - back to Hobby King!Just ordered 10 tt25s and shipping etc was only 10% of the total product price 😊 Will couple them up to a programmable sound unit I bought from a German company which specialises in model electronics. Can be loaded with mp3 or wav sound files 😉Cheers Doug 😎

Hi Boatshed, can't claim originality for the quote, comes from a fridge magnet (!) my GF gave me the day I retired. 😉 She found it on a trip to UK about 3 years ago. I can vouch for it's veracity though! 👍 For instance, just got back from a trip to Italy; was great to tootle around with no pressure to be back by a specific deadline, and to choose my travel times when everyone else was going the other way due to holiday restrictions 😊 Especially on the Brenner pass which was choked in the other direction, He He 😉

Hoylake is just close Dave, and you can park close, its usually quiet, so for testing etc its fine, just a bit small for the bigger scale boats. New Brighton is very busy on these light evenings, parking can be a problem in summer. My other local lake is gautby, a superb lake, big, easy access to all sides, but its not in the best of places. I could go over to Newsham in Liverpool, but you run the risk of kids again, and fishermen, hence Hoylake! and if the wind is down, I can fly on the beach!

Had another play out, and this time had the correct screwdriver to turn the sound down! It sounded much better, but I need to remount the transducers. The thickness of the ply (being very thin) has caused the "tinny" sound, the mounting point needs to be thicker, not too thick, or the volume will be lost, but thicker to increase the deeper tones, and sound more like a twin merlin, which it is.

Hi PaulAs I already have the Action sound unit (Whitby lifeboat engine sound, my model) and a 20w amp I sourced some resonators from Holland www.soundimports.eu/. They were out of stock for the initial order so I bought two lower power exciters to see what they were like. Attached to the back deck of my Trent and plenty of volume but the vibration was very visible. I have now received some 24Watt (Dayton Audio DAEX25FHE-4 Framed High Efficiency 25mm Exciter 24W 4 Ohm) similar to yours and they are attached to the hull sides above the waterline and sound great on the bench. Will be trying on our lake as soon as the weather improves but should be as good as the big 8" speaker I was using and several pounds lighter so the model will sit correctly on the waterline. Thanks for sharing this sound mediumMine are attached by 3M VHB (Very High Bond) adhesive so I am hoping if I need to move or replace I can buy some glue to re-attachDave